To grade chips, we use 6 criteria on the Hitmap, Pixel alive map and Trimming test.
> Hitmap:
Dead pixels present in the area of interest
The total number of dead pixels
> Pixel alive map:
Inefficient pixels present in the area of interest
The total number of inefficient pixels
> Threshold trimming distribution:
Difference of measured threshold mean with respect to the threshold target
The total number of pixels with a threshold higher or lower than 3×RMS
Since each criterion doesn't have the same importance, each chip starts with a value of 6.
If a dead pixels is present in the area of interest or that the total number of dead pixels is superior to 125 (≈ 3% of the 4160 pixels), the chip is directly a C grade.
With a number of dead pixels greater than 208 (= 5% of the 4160 pixels), the chip is graded as BAD.
The other 4 criteria decreases the value by 1 but if two criteria of the same test aren't respect, the value decreases by 3. This allows to grade C a chip if three of these four criteria aren't respected.
If the number of inefficient pixels or the number of pixels with a threshold higher or lower than 3×RMS is greater than 416 (= 10% of the 4160 pixels), the chip is considered as a C grade.
NB: A pixel is considered inefficient when its response is less than or equal to 6.
